This is a continuous effort in responding to the increasing demand for a more precise measurement of relevant genomic information in any viral infection. The knowledge of the presence of a specific viral gene will help in identifying the infectious agent. However, to assess the stage of a disease, to evaluate the efficacy of a treatment, to determine the value of a predictor in the progression of a disease, and to monitor the patient's progression of an infection, a more precise and quantitative analysis of the specific gene would be required. These previously highly research-oriented questions can now begin to be answered in the routine clinical laboratories with the advanced technology of molecular biology such as polymerase chain reaction (PCR) and sequencing and mapping of the restriction nuclease digested fragments. We initiated developmental research in molecular diagnostic technology to meet our clinical study need. The demand for molecular testing for blood products for human immunodeficiency virus, hepatitis C virus (HCV), and hepatitis B virus has grown. Whenever possible, we would improve the basic PCR technique to become a semi-quantitative procedure. During the last few years, we were able to apply the same principles of using PCR as the primary study tool for viral infection such as hepatitis G virus and TT virus. We found that these viruses are transmissible by blood transfusion but cause little or no hepatitis. We also initiated a project to construct an internal standard to be used in RT/PCR for determining HCV RNA. A project to study the unique specificity of repairing enzyme, Mut Y, and its clinical application was also initiated as a collaborative project with the University of Maryland. We will continue to evaluate new testing approaches and specifically concentrate on perfecting quantitation procedures, standardization, and application of molecular testing to blood products.